Chromosome mediated gene transfer is a powerful tool for studies on the organization and regulated expression of genetic information. The potential application of this approach to investigate retrovirus system has been studied. The results demonstrate that the AKR MuLV genome can be stably transferred to uninfected recipient cells via isolated metaphase chromosomes or by lipochromosomes. Although AKR virus are not able to infect heterologous cells, chromosome-mediated and lipochromosome mediated transfection resulted in the establishment of productive AKR-MuLV infection in mink cells. Thus, the use of chromosomes or lipochromosomes to transfer viral genes can circumvent the natural host restriction barrier. In other experiments SV40 viral genome has been successfully transferred to non-infected cells at a high frequency via liposome encapsulated DNA.